Container for storing or transporting liquefied gases at low temperature



3,150,797 ING LIQUEFIE AMAMoTo Sept. 29, 1964 Inventor By f l @www0-74W L @may United States Patent O CONTAINER FOR STRING R TRANSPGRTING LIQUEFIED GASES AT LOW TEMPERATURE Katsuro Yamamoto, Tokyo, Japan, assignor to Couch International Methane Limited, Nassau, Bahamas, a

Bahamian company Filed May 23, 1961, Ser. No. 112,029 Claims priority, application-Japan Aug. 3, 1960 Claims. (Cl. 220-15) This invention relates to a container for storing or transporting liquefied gases at about atmospheric pressure and at a low temperature, in particular for storing or transporting liquefied natural gas, liqueed methane, liquefied propane or liquefied nitrogen.

We have proposed containers of the above kind having in general a structure comprising a rigid outer shell, heat insulating material adjacent -to the inner surfaces of the rigid outer shell, an inner tank located in the space enclosed by the rigid outer shell, said inner tank being made of a material not losing its strength and ductility at the low temperature of the liquid .and being supported by the heat insulating material adjacent to the bottom wall of the rigid outer shell.

The temperature of the liquefied gas in the inner tank is often very low indeed. In the case of liquefied natural gas a-t atmospheric pressure the temperature is for instance as low as minus 160 degrees centigrade. In the case of liquefied nitrogen the temperature is even lower. When in unloaded conditon the inner tank will be at ambient temperature, say plus 20 degrees centigrade.

In other words during normal use the tempera-ture of the inner tank will vary between ambient temperature and minus 160 degrees centigrade or lower. Consequently the inner tank will contract and expand substantially during normal use.

Various proposals have already been made to secure the inner tank in the space enclosed by the heat insulated rigid outer shell in such a way that it is free to contract and expand that shifting and tilting of it is prevented and that the influx of ambient hea-t to the liquid in the inner tank is kept as low as possible.

It is an object of the invention to provide a construction for securing the inner tank in the space enclosed by the heat insulated rigid outer shell, which fulfills the above mentioned requirements which has the advantage of being extremely simple and inexpensive and which has the additional .advantage that the tank can be easily mounted in heat insulated space.

Therefore the container according to the invention is characterized in that it comprises keys and keyways extending vertically along the vertical side walls of the inner tank, each key fitting in a corresponding keyway, each key having a length smaller than the length of the corresponding keyway and each key having a width substantially equal to the width of the corresponding keyway.

The invention will now be further explained with reference to the drawings in which FIGURE 1 is a vertical cross sectional view of a container embodying the invention.

FIGURE 2 is a horizontal cross sectional view of the same.

FIGURE 3 is a vertical cross sectional view of a container embodying a modified construction according to the invention.

FIGURE 4 is a fragmentary vertical cross sectional view showing a modified form of the key and keyway construction according to the invention.

FIGURE 5 is a fragmentary horizontal cross sectional view of the same.

In the drawings which illustrate some preferred emj bodiments of the present invention reference numeral 1 ice designates a rigid outer shell, numeral 2 heat insulating material adjacent to the inner surfaces of the rigid outer shell 1 and numeral 3 an inner tank. The heat insulating material 2 must be of a kind resistant to the low temperatures of the liquid which i-s to be stored in the container. Suitable heat insulating materials are for example balsa wood or quippo. Other suitable heat insulating materials can however also be used. The inner tank 3 is preferably made of a metal not losing its strength and ductility at the very low 4temperatures of the liquid to be stored in the container.

Suitable metals are aluminium or stainless steel.

The inner tank 3 is provided with keys 4 or 4 extending along the vertical side walls 17 of the inner tank 3. In the construction as shown in FIGURES 1, 2 and 3 the keys 4 are secured to all the vertical side walls 17 for instance by means of welding. Said keys 4 co-operate with keyways 5 located in the heat insulating material 2. Preferably blocks 11 are used. These blocks 11 are made of a strong material having good heat insulating properties such as hardwood. The blocks 11 are firmly secured to the inner surface of the rigid outer shell 1 and the keyway 5 is formed in the block 11. The middle part of each vertical wall 17 is provided with a key 4. Each key 4 ts in the corresponding keyway 5, the width of the key 4 being substantially equal to the width of the corresponding keyway 5 but the length of the key 4 being shorter than the length of the corresponding keyway 5. The inner tank 3 is supported by a bottom layer of heat insulating material 18.

The keys 4 and the keyways 5 as shown in FIGURE l are rather short. The keys 4 and the keyways 5 as shown in FIGURE 3 are almost as long as the height of inner tank 3. It will be clear that the length of the keys 4 can be varied at will, provided that the corresponding keyways 5 have a length longer than the length of the keys 4.

Each keyway 5 is in close contact with the side surfaces 6 and 7 of the corresponding key 4 whereas clearances 8, 9 and 10 are present respectively between the head of the key 4 and the bottom of the keyway 5, between the upper end of the key 4 and the upper wall of the keyway 5, and between the lower end of the key 4 and the lower wall of the keyway 5. It will thus be understood that the keys 4 will be free to slide in the keyway 5 .in a vertical direction and also to slide Vin the keyway 5 to and away from the bottom of the keyway 5.

It will Abe recognized that the inner tank 3 is free to expand and contract in all directions but is held against displacement within the heat insulated outer shell 1. Also tilting of the inner tank 3 is prevented by the keys 4 and the keyways 5.

The construction according rto FIGURE 3 is in principle the same as the construction according to FIG- URES 1 and 2 only the keys 4 and the keyways 5 are longer.

It will be readily understood that the heat insulating material 2 on the inner sunface of the rigid outer shell 1 can be provided with the keys and that the inner tank 3 can be provided with the corresponding keyways.

Such an arrangement is illustrated in FIGURES 4 and 5. As shown a keyway 5 is formed in the vertical side wall 17 of the inner tank 3. A corresponding key 4 is embedded in the heat insulating material 2. The reference numeral 14 designates a -block of hardwood secured to the inner surface of the outer shell 1. The key 4 is secured to the Iblock 14 by means of a bolt 15. The relationship between the key 4 and the keyway 5 is quite the same as that described in connection with FIGURES 1, 2 and 3.

The keys 4 or 4 and the keyways 5 or 5 being provided along the vertical side walls 17 of the inner tank 3, act to support the latter intermediate the top and bottom thereof against any tilting or movement whatsoever relative to the heat insulated rigid outer shell 1. The short keys 4 as shown in FIGURE 1 are preferably disposed substantially at the same level as the center of gravity of the inner tank 3. Instead each vertical side wall 17 can be provided with a pair of keys, one key being disposed above and one key being disposed below the center of gravity of the inner tank 3. As shown in FIGURE 3 each vertical sidewall 17 can however also be provided with one long key 4 only.

The intertting relationship between the keys 4 or 4 and the respective keyways S or restrains in a perfect manner any displacement of the inner tank 3 resulting from the rocking or tilting of the ship while allowing eX- pansion and contraction of the inner tank 3 not only in horizontal direction but also in a vertical direction. In other words the inner tank 3 is preferably free to contact and expand with changes in temperature. In addition the inner tank 3 is completely thermally insulated from the rigid outer shell 1 or from the ships structure.

The container according to the invention is in particular destined for use on a ship. It can however also be used for landstorage or for transport over land.

In the case that the container is destined for use on a ship, the hull, or in the case of a double hull ship, the inner hull can be used as the rigid outer shell 1.

I claim:

l. A container for storing or transporting liquefied gases at about atmospheric pressure and at a very low temperature, comprising (a) a rigid outer shell,

(b) an insulating sheet of heat insulating material supported by and within said outer shell,

(c) a liquid-impervious inner tank made of a material not losing its strength and ductility at the low temperature of the liquid, and being located within said insulating shell,

(d) the bottom of said tank resting on and supported by an adjacent surface of said insulating shell,

(e) said inner tank having vertical side walls and a top wall,

(f) said inner tank lbeing subject to a definite large degree of thermal contraction and expansion due to the temperature difference between the empty condition when ythe tank is at ambient temperature and the condition in use, when the tank contains eX- tremely cold liqueed gas,

(g) said side walls and top wall being `spaced from the adjacent side surface of said insulating shell sufciently to permit said thermal contraction and expansion to occur without interference of the adjacent surfaces,

(h) a plurality of sets of mating keys and keyways eX- tending vertically between the vertical side walls of the inner tank and of the adjacent heat insulating shell, a keyway of each set being fixed to one of said last members and the mating key of each set being iixed to the other of said members so as to permit 4 relative vertical contraction and expansion between the inner tank and the insulating shell,

(i) there being two sets of said keyways lying on opposite sides of said tank in a common vertical plane,

(j) and the remaining keyways lying in a second common plane perpendicular to the rst plane,

(k) said sets of keyways being so arranged that lateral expansion and contraction of the inner tank tends to move the keys deeper or less deeply into the keyways,

(l) each keyway being sufficiently deep to permit such lateral motion, and being of such Width as to snugly engage the sides of its associated key, and of suicient length to prevent tilting of said inner tank by said snug side engagement.

2. The container as claimed in claim l in which the inner tank is prismatic and in which the keys and keyways are located in the middle part of each vertical side wall.

3. The container as claimed in claim 1 in which each keyway is formed as a groove in a block of hardwood secured to the rigid outer shell.

4. The container as claimed in claim 1 in which each keyway is formed as a groove in the heat insulating material adjacent to the inner surface of the rigid outer shell.

5. A container for storing or transporting liquefied gases at about atmospheric pressure and at a low temperature, comprising a rigid outer shell, heat insulating material adjacent to the inner surfaces of the rigid outer shell, an inner tank located in the space enclosed by the rigid outer shell, said inner tank being made of a material not losing its strength and ductility at the low temperature of the liquid and being supported by the heat insulat- -ing material adjacent to the bottom wall of the rigid outer shell, keys and keyways extending vertically along the ver-tical side walls of the inner tank each key fitting in a corresponding keyway, each key having a length smaller than the length of the corresponding keyway, a lateral dimension less than the depth of a corresponding keyway, and each key having a width substantially equal to the width of the corresponding keyway, each key being secured to the inner surface of the rigid outer shell and each keyway being formed as a groove in a vertical side wall of the inner tank whereby said keys will be free to slide in the corresponding keyways in a vertical direction and free to slide to and away from the bottoms of said keyways.

References Cited in the file of this patent UNITED STATES PATENTS 228,602 Butler June 8, 1880 2,306,275 Murray Dec. 22, 1942 2,545,686 Collins Mar. 20, 1951 2,807,143 Schnellhardt Sept. 24, 1957 2,905,352 Henry Sept. 22, 1959 2,954,003 Farrell et al Sept. 27, 1960 2,955,415 Long Oct. 1l, 1960 

1. A CONTAINER FOR STORING OR TRANSPORTING LIQUEFIED GASES AT ABOUT ATMOSPHERIC PRESSURE AND AT A VERY LOW TEMPERATURE, COMPRISING (A) A RIGID OUTER SHELL, (B) AN INSULATING SHEET OF HEAT INSULATING MATERIAL SUPPORTED BY AND WITHIN SAID OUTER SHELL, (C) A LIQUID-IMPERVIOUS INNER TANK MADE OF A MATERIAL NOT LOSING ITS STRENGTH AND DUCTILITY AT THE LOW TEMPERATURE OF THE LIQUID, AND BEING LOCATED WITHIN SAID INSULATING SHELL, (D) THE BOTTOM OF SAID TANK RESTING ON AND SUPPORTED BY AN ADJACENT SURFACE OF SAID INSULATING SHELL, (E) SAID INNER TANK HAVING VERTICAL SIDE WALLS AND A TOP WALL, (F) SAID INNER TANK BEING SUBJECT TO A DEFINITE LARGE DEGREE OF THERMAL CONTRACTION AND EXPANSION DUE TO THE TEMPERATURE DIFFERENCE BETWEEN THE EMPTY CONDITION WHEN THE TANK IS AT AMBIENT TEMPERATURE AND THE CONDITION IN USE, WHEN THE TANK CONTAINS EXTREMELY COLD LIQUEFIED GAS, (G) SAID SIDE WALLS AND TOP WALL BEING SPACED FROM THE ADJACENT SIDE SURFACE OF SAID INSULATING SHELL SUFFICIENTLY TO PERMIT SAID THERMAL CONTRACTION AND EXPANSION TO OCCUR WITHOUT INTERFERENCE OF THE ADJACENT SURFACES, (H) A PLURALITY OF SETS OF MATING KEYS AND KEYWAYS EXTENDING VERTICALLY BETWEEN THE VERTICAL SIDE WALLS OF THE INNER TANK AND OF THE ADJACENT HEAT INSULATING SHELL, A KEYWAY OF EACH SET BEING FIXED TO ONE OF SAID LAST MEMBERS AND THE MATING KEY OF EACH SET BEING FIXED TO THE OTHER OF SAID MEMBERS SO AS TO PERMIT RELATIVE VERTICAL CONTRACTION AND EXPANSION BETWEEN THE INNER TANK AND THE INSULATING SHELL, (I) THERE BEING TWO SETS OF SAID KEYWAYS LYING ON OPPOSITE SIDES OF SAID TANK IN A COMMON VERTICAL PLANE, (J) AND THE REMAINING KEYWAYS LYING IN A SECOND COMMON PLANE PERPENDICULAR TO THE FIRST PLANE, (K) SAID SETS OF KEYWAYS BEING SO ARRANGED THAT LATERAL EXPANSION AND CONTRACTION OF THE INNER TANK TENDS TO MOVE THE KEYS DEEPER OR LESS DEEPLY INTO THE KEYWAYS, (L) EACH KEYWAY BEING SUFFICIENTLY DEEP TO PERMIT SUCH LATERAL MOTION, AND BEING OF SUCH WIDTH AS TO SNUGLY ENGAGE THE SIDES OF ITS ASSOCIATED KEY, AND OF SUFFICIENT LENGTH TO PREVENT TILTING OF SAID INNER TANK BY SAID SNUG SIDE ENGAGEMENT. 